The invention relates to a storage vessel of cryogenic gas, including compressed cryogenic gas, particularly a cryo-pressure tank for a motor vehicle, having a storage volume for accommodating the stored gas. The invention further relates to a use of such a storage vessel in the case of a motor vehicle.
For operating motor vehicles by means of hydrogen as the fuel, gas is stored in a supercritical state in a special compression-proof vessel. In this case, the cryogenic gas is stored at a high pressure (13 bar to 350 bar) in the gaseous state. For this purpose, it has to be avoided that heat is carried from the environment into the storage vessel. The storage vessel therefore requires a very good, as a rule, double-walled super-insulation with a high vacuum.
When filling or refueling such a storage vessel with cryogenic gas, its storage content also has to be maintained at a sufficiently low temperature. Furthermore, the temperature prevailing in the storage vessel has to be measured in a precise manner at expenditures that are as low as possible.
According to the invention, a storage vessel of cryogenic compressed gas, particularly a cryo-pressure tank for a motor vehicle, is created, which has a storage volume for accommodating the stored gas. A mixing device for mixing the gas stored in the storage volume is provided in the storage volume.
The solution according to the invention is based on the recognition that, when refueling a conventional cryo-pres sure tank, a thermal layering occurs in the stored supercritical gas immediately after the refueling. This means that warm gas accumulates in the upper area of the storage volume and colder gas accumulates in the lower area of the storage volume. For determining levels of the storage volume by means of the measured quantities of pressure and temperature, a very precise measurement of the average temperature of the stored gas would be required which, in the case of such a layering, would be possible only at higher expenditures, for example, by use of several temperature sensors.
Instead, the mixing device according to the invention for mixing the gas stored in the storage volume results in a mixing of the above-mentioned layering and in making the temperature of the stored gas uniform also during and immediately after the refueling. The temperature of the gas can therefore be measured in a highly precise manner in the case of the storage vessel according to the invention, even by use of only one temperature sensor. Furthermore, the solution according to the invention avoids that tensions could occur at the wall or housing of the storage vessel because of regionally different temperatures. Such tensions could reduce the service life expectancies of the storage vessel.
The mixing device according to the invention is particularly preferably designed with a movably disposed body. Such a body can be moved actively or passively. By means of the movement, the body displaces gas in front of it in the storage volume, while simultaneously gas can flow in at the rear at the body. As a result, a flow is generated in the gas which contributes to the mixing of the gas.
It is particularly advantageous to dispose the movably disposed body in a displaceable manner. The displaceable bearing can be implemented in a constructively very simple fashion, and simultaneously results in a wide range of motion for the body in the, as a rule, elongated storage volume required for the storage vessel.
The displaceable bearing of the movably disposed body is preferably oriented in the longitudinal direction of the pertaining vehicle. Because of its constant acceleration and braking during the driving operation, the vehicle experiences its strongest inputs of impulses in its main driving direction. These impulses may advantageously be utilized for the movement of the body used according to the invention as the mixing device. In that the body provided according to the invention is displaceably disposed toward the longitudinal vehicle direction, it is subjected in this moving direction to the acceleration impulses acting upon it by way of the vehicle. Simultaneously, the body is subjected to its inertia and to a certain friction at its bearing. This interaction of the acceleration impulse, the inertia and the friction has the result that the body is moving again and again relative to its bearing and, as a result, contributes to a mixing of the gas stored in the storage vessel.
Particularly preferably, the movably disposed body is additionally or exclusively disposed in a swivelable manner. By way of such a bearing, a swiveling motion of the body is defined, which may be directed back and forth in the manner of a pendulum or may be oriented in the manner of a circular path or a helical path over an at least longer distance in one rotating direction. The swiveling motion can be carried out in a simple manner and can be utilized in a targeted fashion in order to generate a conveying motion in the storage volume, which results in a whirl-type mixing of the gas.
It is further advantageous according to the invention for the movably disposed body to be disposed in a freely movable manner. In the case of a movement triggered by means of an impulse transmission, the free mobility leads to particularly large movement amplitudes. After a distance of free mobility, these movements can be braked in a targeted manner particularly by way of elastic elements and may also be reversed in the opposite direction.
Furthermore, the movably disposed body is preferably designed as a disk penetrating the storage volume. The disk has a large face by which it can be moved through the storage volume. When it is moved in this manner, it results in a large volume displacement while the moving path is short.
A further preferred shape of the body movably disposed according to the invention is that of a pendulum. The pendulum has a mass body which is linked to a pivot bearing by way of a comparatively low-mass rod. The mass body creates a large mass moment of inertia while the overall mass of the arrangement is comparatively low. This comparatively low overall mass is advantageous specifically with respect to the weight restrictions existing in the field of vehicle construction.
The movably disposed body is further preferably designed with at least one through-opening. The through-opening creates a duct through which a partial flow can enter, while, another partial flow is pushed along in front of the rest of the body. Thereby, partial flows are formed, which are oriented in opposite directions and together result in an advantageous swirling of the stored gas.
With the thus created advantages, the invention correspondingly is also aimed in a targeted manner at a use of such a storage vessel in a motor vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.